This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 from an application for PROJECTION TYPE VIDEO DISPLAY APPARATUS USING A PROGRESSIVE SCANNING MODE earlier filed in the Korean Industrial Property Office on the 13th of June 1998 and there duly assigned Ser. No. 22158/1998.
1. Technical Field
The present invention relates to a projection type video display apparatus and, more particularly, to a projection type video display apparatus using a progressive scanning mode. The apparatus is capable of preventing resolution of a screen from decreasing by means of converting a video signal of an interlaced scanning mode, inputted from an external source, to a video signal of a progressive scanning mode.
2. Description of the Prior Art
Currently, a projection type video display apparatus is broadly used as an apparatus for displaying a video signal inputted from an external source (that is, a video signal for a television or from a video cassette recorder) on a wide screen. Such projection type video display apparatus, in general, displays a video signal on the wide screen with a liquid crystal display or a cathode-ray tube.
However, the projection type video display apparatus which uses a cathode-ray tube to display the video on the wide screen with three pixels called red, green and blue adopts an interlaced scanning mode as the mode for displaying the video.
As a result, if the size of the video being displayed on the wide screen is enlarged or the watching distance is decreased, resolution of the video decreases because of the roughness of the video being displayed on the wide screen. Additionally, the projection type video display apparatus described above needs another encoding device in order to display video received from a computer system. Accordingly, the projection type video display apparatus has to adopt a flicker filter to remove a flickering phenomenon which occurs when an encoded signal from the encoding device is converted to a red-green-blue signal. However, when the projection type video display apparatus has to adopt the flicker filter, the resolution of the video decreases due to distortion of the video signal.
Therefore, it is an object of the present invention to provide a projection type video display apparatus using a progressive scanning mode, which is capable of preventing resolution of a screen from decreasing by converting a video signal of an interlaced scanning mode, inputted from an external source, to a video signal of a progressive scanning mode.
In order to achieve the above object, the present invention provides a projection type video display apparatus using a progressive scanning mode, which comprises: signal selecting means for receiving a plurality of video signals from an external source and for outputting one of the plurality of video signals in response to a first control signal; progressive scanning conversion means for converting the video signal from the signal detecting means to a video signal of a progressive scanning mode in response to a second control signal; cathode-ray tube driving means for amplifying the video signal converted by the progressive scanning conversion means to output a red-green-blue signal; progressive convergence means, responsive to a third control signal, for outputting a progressive convergence signal for minimizing a difference between incidence angles of each of the red, green and blue components of the red-green-blue signal outputted from the cathode-ray tube driving means; a cathode-ray tube for outputting the red-green-blue signal from the cathode-ray tube driving means to a user in response to the progressive convergence signal; and control means for supplying the first control signal to the signal selecting means in response to a selection control signal from the user in order to select the video signal, for supplying the second control signal to the progressive scanning conversion means in order to convert the video signal from the signal selecting means to the video signal of the progressive scanning mode, and for supplying the third control signal to the progressive convergence means.
In order to achieve the above object, the present invention provides a projection type video display apparatus using a progressive scanning mode, which comprises: television signal processing means for receiving a television signal from an external source, for separating a video signal from the television signal, for amplifying the separated video signal, and for supplying the amplified video signal to the signal selecting means; computer signal processing means for receiving a computer video signal from the external source, and for converting the computer video signal to a video signal of an interlaced scanning mode in response to a first control signal; signal selecting means for receiving the television video signal, the computer video signal and an external video signal from said television signal processing means, the computer signal processing means and the external source, respectively, and for outputting one of the television video signal, the computer video signal and the external video signal in response to a second control signal; progressive scanning conversion means for converting the video signal outputted from the signal selecting means to a video signal of a progressive scanning mode in response to a third control signal; cathode-ray tube driving means for amplifying the video signal from the progressive scanning conversion means to a red-green-blue signal; progressive convergence means, responsive to a fourth control signal, for outputting a progressive convergence signal to minimize a difference between incidence angles of each of the red, green and blue components of the red-green-blue signal outputted from the cathode-ray tube driving means; a cathode-ray tube for outputting the red-green-blue signal from the cathode-ray tube driving means to a user in response to the progressive convergence signal; and control means for supplying the first control signal to the computer signal processing means in order to convert the computer video signal to a video signal of the interlaced scanning mode, for supplying the second control signal to the signal selecting means in order to select the video signal in response to a selection control signal from the user, for supplying the third control signal to said progressive scanning conversion means in order to convert the video signal from the signal selecting means to the video signal of the progressive scanning mode, and for supplying the fourth control signal to the progressive convergence means.
In order to achieve the above object, the present invention provides a projection type video display apparatus using a progressive scanning mode, which comprises: signal detecting means for receiving a plurality of video signals from an external source and for outputting one of the plurality of video signals in response to a first control signal; progressive scanning conversion means for converting the video signal from the signal detecting means to a video signal of a progressive scanning mode in response to a second control signal; computer signal processing means for receiving a computer video signal from the external source and for converting the computer video signal to a video signal of the progressive scanning mode in response to a third control signal; video signal selecting means, responsive to a fourth control signal, for outputting one of the video signal of the progressive scanning mode and the computer video signal inputted from the progressive scanning conversion means and the computer signal processing means, respectively; cathode-ray tube driving means for amplifying the video signal from the video signal selecting means to a red-green-blue signal; progressive convergence means, responsive to a fifth control signal, for outputting a progressive convergence signal for minimizing a difference between incidence angles of each of the red, green and blue components of the red-green-blue signal outputted from the cathode-ray tube driving means; cathode-ray tube for outputting the red-green-blue signal from the cathode-ray tube driving means to a user in response to the progressive convergence signal; and control means for supplying the first control signal for selecting the video signal to the signal selecting means in response to a selection control signal from the user, for supplying the second control signal to the progressive scanning conversion means in order to convert the video signal from the signal selecting means to the video signal of the progressive scanning mode, for supplying the third control signal to the computer signal processing means in order to convert the computer video signal to the video signal of the progressive scanning mode, for supplying the fourth control signal to the video signal selecting means in order to select one of the video signal and the computer video signal outputted from the progressive scanning conversion means and the computer signal processing means, respectively, and for supplying the fifth control signal to said progressive convergence means.
In the projection type video display apparatus according to the present invention as described above, the video signal of the interlaced scanning mode, inputted from the external source (such as a video cassette recorder or computer system), is displayed after the scanning mode is converted to the progressive scanning mode. Accordingly, it is able to prevent the resolution of the screen from decreasing.